prime mover

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energy, sources of

energy, sources of, origins of the power used for transportation, for heat and light in dwelling and working areas, and for the manufacture of goods of all kinds, among other applications. The development of science and civilization is closely linked to the availability of energy in useful forms. Modern society consumes vast amounts of energy in all forms: light, heat, electrical, mechanical, chemical, and nuclear. The rate at which energy is produced or consumed is called power, although this term is sometimes used in common speech synonymously with energy.

Types of Energy

Chemical and Mechanical Energy

An early source of energy, or prime mover, used by humans was animal power, i.e., the energy obtained from domesticated animals. Later, as civilization developed, wind power was harnessed to drive ships and turn windmills, and streams and rivers were diverted to turn water wheels (see water power). The rotating shaft of a windmill or water wheel could then be used to crush grain, to raise water from a well, or to serve any number of other uses. The motion of the wind and water, as well as the motion of the wheel or shaft, represents a form of mechanical energy. The source of animal power is ultimately the chemical energy contained in foods and released when digested by humans and animals. The chemical energy contained in wood and other combustible fuels has served since the beginning of history as a source of heat for cooking and warmth. At the start of the Industrial Revolution, water power was used to provide energy for factories through systems of belts and pulleys that transmitted the energy to many different machines.

Heat Energy

The invention of the steam engine, which converts the chemical energy of fuels into heat energy and the heat into mechanical energy, provided another source of energy. The steam engine is called an external-combustion engine, since fuel is burned outside the engine to create the steam used inside it. During the 19th cent. the internal-combustion engine was developed; a variety of fuels, depending on the type of internal-combustion engine, are burned directly in the engine's chambers to provide a source of mechanical energy. Both steam engines and internal-combustion engines found application as stationary sources of power for different purposes and as mobile sources for transportation, as in the steamship, the railroad locomotive (both steam and diesel), and the automobile. All these sources of energy ultimately depend on the combustion of fuels for their operation.

Electrical Energy

Early in the 19th cent. another source of energy was developed that did not necessarily need the combustion of fuels—the electric generator, or dynamo. The generator converts the mechanical energy of a conductor moving in a magnetic field into electrical energy, using the principle of electromagnetic induction. The great advantage of electrical energy, or electric power, as it is commonly called, is that it can be transmitted easily over great distances (see power, electric). As a result, it is the most widely used form of energy in modern civilization; it is readily converted to light, to heat, or, through the electric motor, to mechanical energy again. The large-scale production of electrical energy was made possible by the invention of the turbine, which efficiently converts the straight-line motion of falling water or expanding steam into the rotary motion needed to turn the rotor of a large generator.

Nuclear Energy

The development of nuclear energy made available another source of energy. The heat of a nuclear reactor can be used to produce steam, which then can be directed through a turbine to drive an electric generator, the propellers of a large ship, or some other machine. In 1999, 23% of the electricity generated in the United States derived from nuclear reactors; however, since the 1980s, the construction and application of nuclear reactors in the United States has slowed because of concern about the dangers of the resulting radioactive waste and the possibility of a disastrous nuclear meltdown (see Three Mile Island; Chernobyl; Fukushima).

Environmental Considerations

The demand for energy has increased steadily through much of the late 20th and early 21st cent., not only because of the growing population but also because of the greater number of technological goods available and the increased affluence that has brought these goods within the reach of a larger proportion of the population. For example, despite the introduction of more fuel-efficient motor vehicles (average miles per gallon increased by 34% between 1975 and 1990), the consumption of fuel by vehicles in America increased by 20% between 1975 and 1990. The rise in gasoline consumption is attributable to an increase in the number of miles the average vehicle traveled and to a 40% increase in the same period in the number of vehicles on the road. From 1990 to the mid-2000s, the average fuel efficiency decreased (a trend that had begun in the 1980s), due in part to the increasing use of light trucks as passenger vehicles, but it subsequently began to improve due to increasingly stringent federal standards. The number of miles traveled increased more slowly during the same period, and the total amount of fuel consumed declined for a time due to recession and then increased to around the levels of the mid-2000s.

As a result of the increase in the consumption of energy, concern has risen about the depletion of natural resources, both those used directly to produce energy and those damaged during the exploitation of the fuels or as a result of contamination by energy waste products (see under conservation of natural resources). Most of the energy consumed is ultimately generated by the combustion of fossil fuels, such as coal, petroleum, and natural gas. Although the world has only a finite supply of these fuels, and concern was long focused on decreasing supply, the environmental damage caused by the use of such fuels, especially coal, is a greater concern. The production and combustion of these fuels releases various pollutants (see pollution), such as soot, carbon monoxide and sulfur dioxide, which pose health risks and contribute to acid rain, and carbon dioxide and methane, which contribute to global warming. There are also destructive effects to sensitive wildlands (e.g., the tropical rain forests, the arctic tundra, and coastal marshes) during the exploitation of their resources.

The Search for New Sources of Energy

The environmental consequences of energy production have led many nations in the world to impose stricter guidelines on the production and consumption of energy. Further, the search for new sources of energy and more efficient means of employing energy has accelerated. The development of a viable nuclear fusion reactor is often cited as a possible solution to our energy problems. Presently, nuclear-energy plants use nuclear fission, which requires scarce and expensive fuels and produces potentially dangerous wastes. The fuel problem has been partly helped by the development of breeder reactors, which produce more nuclear fuel than they consume, but the long-term hopes for nuclear energy rest on the development of controlled sources using nuclear fusion rather than fission. The basic fuels for fusion are extremely plentiful (e.g., hydrogen, from water) and the end products are relatively safe. The basic problem, which is expected to take decades to solve, is in containing the fuels at the extremely high temperatures necessary to initiate and sustain nuclear fusion.

Another source of energy is solar energy. The earth receives huge amounts of energy every day from the sun, but the problem has been harnessing this energy so that it is available at the appropriate time and in the appropriate form. For example, solar energy is received only during the daylight hours, but more heat and electricity for lighting are needed at night. Technological advances in photovoltaic cells and in the cost of the their production have made solar energy a more financially competitive source of energy.

Wind energy, which has long been used as a source of mechanical energy for milling and pumping, can also be used to produced electricity. Modern propellerlike wind turbines, often joined together in wind farms, can produce 1.5 MW or more of electricity and can serve as a significant source of electric energy in plains and coastal areas (including offshore locations). Wind turbines have been most extensively used in Europe, but also have been used in many areas in the United States.

Some scientists have suggested using the earth's internal heat as a source of energy. Geothermal energy is released naturally in geysers and volcanoes. In California, some of the state's electricity is generated by the geothermal plant complex known as the Geysers, which has been in production since 1960, and in Iceland, which is geologically very active, roughly 90% of the homes are heated by geothermal energy. Still another possible energy source is tidal energy. A few systems have been set up to harness the energy released in the twice-daily ebb and flow of the ocean's tides, but they have not been widely used, because they cannot operate turbines continuously and because they must be built specifically for each site.

Another direction of research and development is in the search for alternatives to gasoline. Possibilities include methanol, which can be produced from wood, coal, or natural gas; ethanol, an alcohol produced from grain, sugarcane, and other agriculture plants and currently used in some types of U.S. motor fuel (e.g., gasohol and E85, a mixture of 85% ethanol and 15% gasoline); and compressed natural gas, which is much less polluting than gasoline, but all of these contribute to a greater or lesser degree to air pollution and global warming. Hybrid vehicles, which use electric power from batteries in addition to an internal combustion engine, are less polluting, but rely in part on the engine to recharge the batteries. Fully electric vehicles, which are increasingly common, are significantly less polluting if the energy used to charge them is primarily derived from hydroelectric, solar, or wind sources.


See G. R. Harrison, The Conquest of Energy (1968); F. Barnaby, Man and the Atom: The Uses of Nuclear Energy (1971); W. G. Steltz and A. M. Donaldson, Aero-Thermodynamics of Steam Turbines (1981); T. N. Veziroglu, ed., Alternative Sources of Energy (1983 and 1985) and Renewable Energy Sources (Vol. 4, 1984); G. L. Johnson, Wind Energy Systems (1985).

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prime mover

[′prīm ′müv·ər]
A muscle that produces a specific motion or maintains a specific posture.
(mechanical engineering)
The component of a power plant that transforms energy from the thermal or the pressure form to the mechanical form.
A tractor or truck, usually with four-wheel drive, used for hauling tasks.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Prime mover

The component of a power plant that transforms energy from the thermal or the pressure form to the mechanical form. Mechanical energy may be in the form of a rotating or a reciprocating shaft, or a jet for thrust or propulsion. The prime mover is frequently called an engine or turbine and is represented by such machines as waterwheels, hydraulic turbines, steam engines, steam turbines, windmills, gas turbines, internal combustion engines, and jet engines. These prime movers operate by either of two principles: (1) balanced expansion, positive displacement, intermittent flow of a working fluid into and out of a piston and cylinder mechanism so that by pressure difference on the opposite sides of the piston, or its equivalent, there is relative motion of the machine parts; or (2) free continuous flow through a nozzle where fluid acceleration in a jet (and vane) mechanism gives relative motion to the machine parts by impulse, reaction, or both. See Gas turbine, Hydraulic turbine, Impulse turbine, Internal combustion engine, Power plant, Reaction turbine, Steam engine, Steam turbine, Turbine

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.

prime mover

1. Any machine that converts fuel (e.g., diesel oil, gasoline, or natural gas) or steam into mechanical energy.
2. A powerful truck, tractor, or the like.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

prime mover

a. the source of power, such as fuel, wind, electricity, etc., for a machine
b. the means of extracting power from such a source, such as a steam engine, electric motor, etc.
2. (in the philosophy of Aristotle) that which is the cause of all movement
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The significantly lower ability of women to activate muscles involved in hand gripping may restrict the magnitude of the RVC driven CAP response of the prime mover for women, considering motor overflow increases with contraction intensity (12) and, therefore, potentially explaining the findings of the present study.
For any value of prime mover PLR and heat allocation fraction, the amount of heat available for the absorption chiller (Qgen, abs, ch) as well as excess heat available for heating can then be computed.
Figure 4 presents the relationship between prime mover electrical power output and heating capacity, which represents an operating curve.
Finally, the wider the scale on which an energy prime mover is deployed, the longer it will take for substitutions to appear.
Jacques Brunschwig and Aryeh Kosman have taken opposing views on the famous problem in chapter 9 of what the prime mover knows.
Ricardo was a prime mover during the early 1920s in the "Anta" subgroup of Modernismo, which urged a nationalistic rediscovery of the land and its indigenous folkloric traditions.
Fernow, chief of the Forestry Division of the Department of Agriculture, who would later be a prime mover in the American Forestry Association.
Indeed, in those days the theory of industrial production saw the machine as the prime mover in production and the worker as a malleable extension of the machine.
He was also the prime mover and signatory of the James Bay Northern Quebec Agreement and the Cree-Naskapi Act on behalf of the Cree people of Northern Quebec.
THE "prime mover" view of a country's economy holds that fluctuations in economic activity reflect, to an important extent, movements in certain fundamental forces.
(Lat, " prime mover " ) In the classical concept of the order of the heavens, the ninth heaven.